This invention relates to multiple port manifolds for air tanks, such as an air storage tank for suppling air to the air-pressure operated or supplying components of a truck or semi-trailer, such as to an air compressor or to the air brakes.
Commonly, fittings on metal air tanks have been made by punching or forming a hole in the wall of the tank and welding a threaded bushing at the hole, having internal NPT-type pipe threads. The connector or device to be mounted or supported would have corresponding NPT interference-fit threads and would thus be connected to communicate with the tank interior. Such arrangements have led to persistent leakage problems since NPT-type threads do not reliably hold air pressure, such as where the working pressures may run as high as 150 psi or more.
Thus, for particular tanks, a plurality of such welded bushings have been used, one for each pneumatic line which is extended from the tank, one for the tank inlet, to incorporate a check valve, and still another to incorporate a drain valve to permit condensed water to be drained from the tank, and perhaps another to receive a high pressure release valve.
Commonly, the tank closest to the air compressor is known as a "wet" tank since it receives condensed moisture in the line from the pump. Such wet tanks have thus been required to have some means for draining out the condensed moisture in the form of a bushing-mounted valve, commonly located at the bottom of the tank.
Thus, in some instances, there is a prolification of individual fittings mounted on an outside wall of the tank, such as at an end wall, each providing a separate function, in which the tank interior then acts as a manifold for all of the fittings. Obviously, the likelihood of problems, such as leakage, is increased.
There is accordingly a need for an air tank manifold construction that provides for the elimination of threaded connections, and has provision for incorporating a plurality of functions, including check valve functions and water drainage finctions, which uses reliable push-to-connect fittings for flexible hose connections, and which may be employed for a plurality of functions as may be required in connection with air pressure storage tanks on a motor vehicle.
Lightweight composite air pressure tanks are beginning to replace the traditional metal tanks in truck and semi-trailer operations and the like. Such composite tanks do not lend themselves to conventional attachments such as bushings as have been used in the past in connection with metal tanks. There is accordingly a need for an air tank manifold particularly adapted for use with composite tanks.